I am making a short, text-based game as an extra credit exercise based on the Ruby I have learned so far and I'm having trouble getting classes to read and write variables between each other. I have read extensively and searched for clarification on how to do this but I haven't had much luck. I have tried using @ instance variables and attr_accessible but I can't figure it out. Here is my code so far:

class Game
attr_accessor :room_count
def initialize
@room_count = 0
end
def play
while true
puts "\n--------------------------------------------------"
if @room_count == 0
go_to = Entrance.new()
go_to.start
elsif @room_count == 1
go_to = FirstRoom.new()
go_to.start
elsif @room_count == 2
go_to = SecondRoom.new()
go_to.start
elsif @room_count == 3
go_to = ThirdRoom.new()
go_to.start
end
end
end
end
class Entrance
def start
puts "You are at the entrance."
@room_count += 1
end
end
class FirstRoom
def start
puts "You are at the first room."
@room_count += 1
end
end
class SecondRoom
def start
puts "You are at the second room."
@room_count += 1
end
end
class ThirdRoom
def start
puts "You are at the third room. You have reached the end of the game."
Process.exit()
end
end
game = Game.new()
game.play

I want to have the different Room classes change the @room_count variable so that Game class knows which room to go to next. I am also trying to do this without implementing class inheritance. Thanks!